<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <script src="../../angular-1.5.8/angular.js"></script>
</head>
<body>
    <div ng-app="mainApp" ng-controller="mainController">
        <div>{{123|func}}</div>
    </div>
</body>
<script>
    angular.module('mainApp',[])
        .controller('mainController',function ($scope,$filter){

        })
        .filter('func',function (){
                return function (value){
                    return ('('+value+')')
                }
        })
</script>
</html>